1. Field of the Invention
The present invention relates to a magnetic detection device capable of adjusting the resistance value of a sensor unit including a sensor pattern having magnetoresistance effect films and electrode units without increasing the dimensions of the sensor unit.
2. Description of the Related Art
A magnetic detection device configured to detect an external magnetic field has, for example, a magnetoresistance effect film that utilizes the magnetoresistance effect. The magnetoresistance effect is the change in the electric resistance value in accordance with an external magnetic field applied.
FIG. 11 is an enlarged plan view of a sensor unit 1 of the related art. The sensor unit 1 is configured to include a meandering sensor pattern 2 having the above magnetoresistance effect film, and electrode units 3 and 4 that are connected to ends 2a and 2b of the sensor pattern 2 in its longitudinal direction, respectively.
As illustrated in FIG. 11, a projecting portion 5 that projects outward from the sensor pattern 2 in its width direction (in FIG. 11, in the X direction) is formed integrally with the electrode unit 3.
The resistance value between the electrode units 3 and 4 (hereinafter referred to as the “resistance value of the sensor unit 1”) is measured. When the measured resistance value is greater than that of a fixed resistor unit (not illustrated) connected in series with the sensor unit 1, in order to make the resistance value of the sensor unit 1 match the resistance value of the fixed resistor unit, the sensor pattern 2 is electrically connected to the projecting portion 5 via a conductor 7 at an intermediate position of the sensor pattern 2 to reduce the current path length of the sensor pattern 2. Accordingly, the resistance value of the sensor unit 1 can be adjusted so as to match the resistance value of the fixed resistor unit.
However, the method of adjusting the resistance value of the sensor unit 1 illustrated in FIG. 11 has a problem in that the provision of the projecting portion 5 that projects outward from the sensor pattern 2 in its width direction (in FIG. 1, the X direction) results in an increase in the dimension of the sensor unit 1 in its width direction (in FIG. 11, the X direction).
Japanese Unexamined Patent Application Publication No. 2004-207540 does not disclose a resistance adjustment method for a sensor pattern having magnetoresistance effect films. As illustrated in FIG. 11, furthermore, a space T1 between magnetoresistance effect films that are coupled via a return portion 2c of the sensor pattern 2, which is used in a magnetic detection device, and that face each other is as narrow as about 1 to 10 μm. Thus, it is difficult to form the conductor 7 only within the space T1 so as to establish stable electrical connection between the conductor 7 and the sensor pattern 2 without causing contact failure therebetween because the contact area between the conductor 7 and the sensor pattern 2 is small.